package com.gbei.center.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.security.MessageDigest;

/**
 * MD5处理器 
 * @author ShiLijin 
 */  
public class MD5Encoder {
 
	private static Logger logger = LoggerFactory.getLogger(MD5Encoder.class);
	
 private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
   "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
 
 private Object salt;
 private String algorithm;//MD5、SHA
 
 public static void main(String[] args) {
	logger.info(new MD5Encoder("password", "MD5").encode("admin123"));
}
 
 public MD5Encoder(Object salt, String algorithm) {
  this.salt = salt;
  this.algorithm = algorithm;
 }

 public String encode(String rawPass) {
  String result = null;
  try {
   MessageDigest md = MessageDigest.getInstance(algorithm);
   //加密后的字符串  
   result = byteArrayToHexString(md.digest(mergePasswordAndSalt(rawPass).getBytes("utf-8")));
  } catch (Exception ex) {
  }
  return result;
 }
 
    public boolean isPasswordValid(String encPass, String rawPass) {
        String pass1 = "" + encPass;
        String pass2 = encode(rawPass);

        return pass1.equals(pass2);
    }
    
    private String mergePasswordAndSalt(String password) {
        if (password == null) {
            password = "";
        }

        if ((salt == null) || "".equals(salt)) {
            return password;
        } else {
            return password + "{" + salt.toString() + "}";
        }
    }

 /**
  * 转换字节数组为16进制字串
  * @param b 字节数组
  * @return 16进制字串
  */
 private static String byteArrayToHexString(byte[] b) {
  StringBuffer resultSb = new StringBuffer();
  for (int i = 0; i < b.length; i++) {
   resultSb.append(byteToHexString(b[i]));
  }
  return resultSb.toString();
 }

 private static String byteToHexString(byte b) {
  int n = b;
  if (n < 0)
   n = 256 + n;
  int d1 = n / 16;
  int d2 = n % 16;
  return hexDigits[d1] + hexDigits[d2];
 }
}